1. Field of the Invention
The present invention relates to an optical pickup, optical information recording device, optical information recording method, optical information reproduction device, optical information reproduction method and optical information recording medium, and is preferably applied to an optical information recording and reproducing device that records information on a recording medium by using an optical beam and reproduces the information from the recording medium by using an optical beam, for example.
2. Description of the Related Art
As an optical information recording and reproducing device, an optical disc device is popular: The optical disc device uses a disc-shaped optical disc as an information recording medium, which includes Compact Disc (CD), Digital Versatile Disc (DVD) and “Blu-Ray Disc (Registered Trademark: also referred to as ‘BD’).”
The optical disc device is designed to record on an optical disc various types of information, such as various types of content (like music content and video content) and various types of data for computers. In recent years, the amount of information is increasing as the technique of high-definition images develops and the quality of sound improves. Since the number of contents to be recorded on one optical disc is increasing, the capacity of the optical disc may need to increase.
A method to increase the capacity of an optical disc is proposed in Jpn. Pat. Laid-open Publication No. 2006-78834 (FIG. 1): It employs a technique of making two optical beams together and forms a hologram to record information.